The fornix and the vulva cerebri: Naughty names for neuroanatomy.

How the Brain Got Its Buttocks

Sixteenth-century anatomists couldn't keep their minds out of the gutter.

Images from Thomas Willis'On the Anatomy of the Brain, published in 1664

There are so many obscure specializations, subspecializations and subcortical subspecializations within the brain sciences that even the sharpest brain has scarcely enough brainpower to learn everything there is to know about itself. But if there's one fact that the teacup-Yorkie-sized prune in your head might want to ponder, it's that it shares a peculiar past with something considerably lower in your anatomy—your genitalia. I don't mean that our brains and reproductive organs share some embryological or evolutionary history, but rather that they were once (and, to some extent, still are) entwined in the language of the body. What this odd story reveals is that the ancient anatomists were major dickheads. We all were, back then.

Régis Olry, of the University of Quebec, and Duane Haines, of the University of Mississippi, brought the whole sordid tale to light in an intriguing pair of articles for the Journal of the History of the Neurosciences. These "historians of neuroanatomy" (yes, there is such a profession, and we should be grateful for it) reviewed a very old, circuitous medical literature and found that the human brain was once described as comprising its very own vulva, penis, testicles, buttocks, and even an anus. In fact, part of the cerebrum is still named in honor of long-forgotten whores.

In their first article from 1997, epochs ago in academic terms, Olry and Haines revealed the surprising origins of the term "fornix." For those illiterate in neuroanatomy, which I'll assume is 99.9 percent of you, the fornix is a fibrous, arching band of nerve fibers that connects the hippocampus and the limbic system, and spans certain fluid-filled chambers of the brain known as ventricles. You'd have numerous and noticeable problems if your fornix weren't functioning properly, including serious impairments in spatial learning and overall navigation.

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Some basics of etymology. Although today fornix is reserved almost exclusively for anatomical structures—there's also a fornix of the conjunctivae, which connects the membranes of the eye, as well as several other bodily fornices, but let's move on—the word originally held an architectural connotation, coming from the Latin for "arch." Olry and Haines point out that Roman architects during the first century B.C. created wooden rooms with vaulted ceilings, called fornices. When such rooms were made of brick, they were called cameras (There's a separate etymological history involving the modern-day camera and these brick-arched Roman rooms, but we're focusing on the fornix here.)

Now, none of this is terribly salacious—and it's quite possible that the first neuroanatomist ever to use this term, the 17th-century Englishman Thomas Willis, had nary a dirty thought in mind. But it's also a fact that the wood-vaulted rooms of old were used expressly for the plying of a particular trade in ancient Rome, prostitution (hence, fornication). "The real etymology of the term 'fornix,' " concluded Olry and Haines, "is therefore related to the form of the roof of the third ventricle, but also to the sexual intercourse which occurred in such rooms, these rooms being compared with this ventricle." It's merely an ironic twist that the fornix helps to regulate human sexual behavior as part of the limbic system; as the authors point out, the name was bestowed long before anyone knew this function.

In any event, once they'd put the fornix to bed, Olry and Haines waited another decade or so before they revisited the sexy third ventricle. In a follow-up article from 2008, they exposed some more, rather curiously named features from the same part of the brain. When the mid-16th century Italian anatomist, Matthaeo Realdo Colombo, peered into the small recess adjoining the anterior commissure and the dividing line of the fornix's two columns, report Olry and Haines, he saw what looked like a lubricated vulva—and called it the vulva cerebri. Perhaps that's not too surprising, given that Colombo is also widely credited as being the anatomist who first "discovered" the clitoris (the real one, down there).

The authors point out there's a bit of a mystery about precisely which hole Colombo was poking with his Italian probe. It might, in fact, have been the more posterior opening identified by the 17th-century Dutch anatomist Isbrand van Diemerbroeck, who found, in Colombo's groove, "the hole of the anus." Your brain's anus, incidentally, is what we'd now call the common posterior opening of the midbrain's aqueduct, which spills into the third ventricle. There are so many defecation-related puns about intelligence to be made here that my mind is cramping up, so, shit, I'll just leave that part up to you assholes.

Now, van Diemerbroeck didn't just see lady bits in the brain; if anything, he and his fellow anatomists envisioned it as an essentially hermaphroditic organ. After all, not only did it have a vulva cerebri, it also possessed a distinctive penis cerebri. René Descartes may have celebrated the pineal gland as the "seat of the soul," but for the less metaphysically minded van Diemerbroeck, as well as one of Descartes' contemporaries, the Danish physician Thomas Bartholin, that structure was more like a penis. This metaphor may have its roots, explain Olry and Haines, in the position of the gland above and between the brain's colliculi, which had already been compared with testicles (as, perhaps, the original "hanging brain").

This cockeyed term, penis cerebri, proved too embarrassing for future scholars and quickly shrank into disuse. Yesterday's penis is today's soulless pineal gland (a stiffer term, to be sure). By the mid-18th-century in France, a real buzz-kill of an anatomist by the name of Jacques Bénigne Winslow was already looking back in disgust at his forebears' indelicate classifications; the ancients, he thought, had their heads in the gutter when it came to what was in their heads. Winslow held these founding fathers of the neurosciences in particular disrepute for their having seen buttocks (eminentiae natiformes) and testicles (eminentiae testiformes) in the colliculi. "The names that were given to these tubercles are very impertinent, and have no resemblance with the things they were derived from." Others begged to differ, and scholars continued to refer to the buttocks and testicles in our brains for centuries after Winslow huffed and puffed about the matter, even into the 20th century. Eventually, however, academic prudery eclipsed asinine antiquarianism.

Still, a spunky remnant of those lost days of brainiac debauchery did slip into the present-day vocabulary. According to Olry and Haines, the glandular portion of the pineal gland can be traced back to its bulbous terminological predecessor, the glans penis. Today we know that the pineal gland produces melatonin, a chemical central to regulating your sleep-wake cycle. So the next time you have jet lag, blame it on your penis.

Olry and Haines weren't the first to scratch their heads over this lurid labeling of our neuroanatomical regions. Joining the prudish Winslow in his disdain, the French anatomist Joseph Auguste Aristide Fort observed in 1902 that the anatomists of past centuries "enjoyed giving indecent names to the different parts surrounding the third ventricle." But Olry and Haines did show exactly how these Renaissance anatomists cast their libidinous eyes upon the gray matter and saw not the glistening engine of our thoughts, but rather our private parts.

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